Karl Fischer titration raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-05-10 and is reviewed periodically as new material appears.
Identity and purity are assessed with several complementary methods. High-performance liquid chromatography can separate creatine from creatinine and related impurities, often with ultraviolet detection. Nuclear magnetic resonance and infrared spectroscopy provide structural confirmation, while Karl Fischer titration measures water content. Elemental analysis and mass spectrometry may be used for additional confirmation, especially in research or forensic settings. No single method captures every quality attribute, so laboratories typically combine results and compare them against a specification.
Creatine monohydrate is sold as a dietary ingredient in some countries and as a food supplement in others. Regulatory frameworks vary, so purity limits, labeling rules, and permitted claims are not globally uniform. In the United States, it falls under dietary supplement rules, whereas the European Union treats it as a food supplement ingredient. Pharmacopeial monographs, where they exist, can provide public quality standards, but not every product is required to meet them. Questions about long-term effects and patterns of use remain areas of active study rather than settled regulatory findings.
Solid creatine monohydrate is generally stable when kept cool and dry, but it can hydrolyze to creatinine over time. Moisture, heat, and acidic conditions accelerate this conversion, which reduces assay values and changes the material's properties. Creatinine is a cyclic dehydration product that is also a normal human metabolite, so its presence in a sample is not necessarily a health concern by itself. In quality testing, creatinine is monitored as a marker of degradation and purity.
Identity and purity are commonly assessed by high-performance liquid chromatography, often with ultraviolet detection, and by spectroscopic techniques such as infrared or nuclear magnetic resonance. These methods can distinguish creatine from creatinine and detect related impurities. Moisture content may be measured by Karl Fischer titration or loss on drying. Particle size, bulk density, and heavy metal limits are additional quality parameters. Not every product is tested by every method, so specifications depend on the intended use and regulatory framework.
Solid creatine monohydrate is generally stable when kept dry and protected from extremes of heat and humidity. In the presence of moisture, it can gradually convert to creatinine, a cyclic dehydration product that has little value for phosphocreatine synthesis. Elevated temperatures and acidic conditions accelerate this conversion in solution. Because the reaction is slow in cool, dry storage, typical shelf lives are measured in years rather than weeks. Packaging that limits moisture and oxygen exposure helps maintain purity.
| Property | Value | Notes |
|---|---|---|
| Purity (typical) | ≥99% by HPLC | Supplement and pharmacopeial grades vary |
| Water content | ≈12.1% theoretical | Measured by Karl Fischer titration |
| Creatinine limit | Often ≤0.1% in pharmacopeial grade | Supplement specifications may differ |
| Storage conditions | 15–25 °C, low humidity | Away from heat and acidic environments |
| Common analytical methods | HPLC–UV, NMR, FTIR, Karl Fischer | Used for identity, assay, and water content |
Commercial creatine monohydrate is typically a white to off-white powder with low odor. It is commonly sold as a fine powder, micronized powder, or larger crystals, but these are physical forms of the same chemical. Purity grades vary, and products may contain small amounts of related substances such as creatinine, dicyandiamide, or moisture. The monohydrate is often selected for supplements and research because its production is well established and its behavior in water is predictable. Analytical certificates usually report assay, loss on drying, and heavy metals.
Creatine monohydrate is a crystalline compound formed from creatine and one water molecule in its solid lattice. Creatine itself is a nitrogen-containing organic acid involved in energy transfer in muscle and other tissues. The monohydrate form is the most common solid form used in research and commercial products because it is stable and easy to handle. The term "monohydrate" refers to the fixed one-to-one ratio of water to creatine in the crystal, not to moisture content. This distinction matters when comparing labels or calculating creatine content.
== Uses == P. rubens is the source of β-lactam antibiotics, principally of penicillins and to a lesser extent, cephalosporins. The species produces three penicillins, benzylpenicillin (G), phenoxymethylpenicillin (V) and octanoylpenicillin (K). Penicillin G is a naturally occurring compound that was first isolated and used as an antibiotic. Penicillins from P. rubens are effective against Gram-positive bacteria such as the species of Bacillus, Clostridium, Corynebacterium, Pneumococcus, Streptococcus, and Staphylococcus. They are clinically used to treat actinomycosis, anthrax, botulism, clostridial infections, diphtheria, empyema, endocarditis, food poisoning (due to Listeria), gas gangrene, meningitis, pneumonia, pericarditis, septicaemia, and syphilis. However, they are useless against Gram-negative bacteria since these bacteria are impermeable to the compounds because of their additional outer cell membrane, as well as some species producing pencillases (β-lactamases) that destroy the penicillin structure (β-lactam ring). However, semisynthetic penicillins like aminopenicillins (ampicillin, amoxicillin, and bacampicillin), carboxypenicillins (carbenicillin and ticarcillin) and ureidopenicillins (mezlocillin, azlocillin, and piperacillin) have been developed that are effective against these bacteria. Cephalosporins, naturally produced by other fungi belonging to the genus Acremonium, are one of the most widely used antibiotics by clinicians and is also produced by P. rubens. However, they are not naturally produced by P. rubens.
=== 1H—13C HSQC === This experiment provides correlations between a carbon and its attached protons. The constant time (CT) version of 1H—13C HSQC is normally used as it circumvents the issue of splitting of signal due to homonuclear 13C—13C J couplings which reduces spectral resolution. The "constant time" refers to the entire evolution period between the two INEPT steps which is kept constant in this experiment. If this evolution period is set to be the inverse of the J-coupling constant, then the sign of the magnetization of those carbons with an odd number of aliphatic carbon attached will be opposite to those with an even number. For example, if the Cβ of leucine appears as a positive peak (2 aliphatic carbons attached), then the Cγ (3 aliphatic carbons attached) and Cα (1 aliphatic carbons attached) would appear negative.
The real chromatographic analysis starts with the introduction of the sample onto the column. The development of capillary gas chromatography resulted in many practical problems with the injection technique. The technique of on-column injection, often used with packed columns, is usually not possible with capillary columns. In the injection system in the capillary gas chromatograph the amount injected should not overload the column and the width of the injected plug should be small compared to the spreading due to the chromatographic process. Failure to comply with this latter requirement will reduce the separation capability of the column. As a general rule, the volume injected, Vinj, and the volume of the detector cell, Vdet, should be about 1/10 of the volume occupied by the portion of sample containing the molecules of interest (analytes) when they exit the column. Some general requirements which a good injection technique should fulfill are that it should be possible to obtain the column's optimum separation efficiency, it should allow accurate and reproducible injections of small amounts of representative samples, it should induce no change in sample composition, it should not exhibit discrimination based on differences in boiling point, polarity, concentration or thermal/catalytic stability, and it should be applicable for trace analysis as well as for undiluted samples. However, there are a number of problems inherent in the use of syringes for injection. Even the best syringes claim an accuracy of only 3%, and in unskilled hands, errors are much larger.
== History == Cattle and sheep have long been known to voluntarily consume seaweed in variable amounts if they have access. Historical evidence suggests that farmers in Ancient Greece deliberately grazed cattle near beaches as a result of the productivity benefits it provided. This was also the case for Icelandic farmers in the 18th century. FutureFeed's Chief Scientist Rob Kinley had a "lightbulb moment" in Canada in the early 2000's, where a Canadian dairy farmer, Joe Dorgan, had been allowing his dairy cows access to stormtoss seaweed that appeared naturally on his property. He reported consistent improvements in animal performance. Dorgan desired to commercialise this concept, but regulations required it be scientifically tested first. Kinley and Professor Alan Freeden were recruited by Dorgan to perform official testing on the nutritional data of this seaweed and to quantify the effects it had on cattle health. Dorgan intended to harvest and sell seaweed as an organic alternative to conventional supplements. However, further testing revealed its ability to reduce methane emissions of livestock. Kinley discovered that this particular form of seaweed was capable of reducing methane production in cattle by up to 20%. Following this discovery, Kinley moved to Australia to partner with CSIRO and James Cook University (JCU) to conduct further testing. A research team at JCU had previously studied the effects of algal feed additives on livestock production systems as part of the Centre for Macroalgal Resources and Biotechnology (MACRO).
from the insulinogenic index (IGI) and the insulin sensitivity index (ISIcomposite). The fasting-based disposition index (SPINA-DI) can be obtained from the product of the secretory capacity of pancreatic beta cells (
Sources: en.wikipedia.org
Until May 1943, almost all penicillin was produced using the shallow-pan method pioneered by the Oxford team, but NRRL mycologist Kenneth Bryan Raper experimented with deep submergence production, in which penicillin mould was grown in a vat instead of a shallow dish. The initial results were disappointing; penicillin cultured in this manner yielded only three to four Oxford units per cubic centimetre, compared to twenty for surface cultures. He got the help of U.S. Army's Air Transport Command to search for similar mould in different parts of the world. Good moulds were found in samples from Chongqing, Bombay and Cape Town. The best sample, however, was from a cantaloupe sold in a Peoria fruit market in 1943. The mould was identified as Penicillium chrysogenum and designated as "NRRL 1951" or "cantaloupe strain". The spores may have escaped from the NRRL. Between 1941 and 1943, Moyer, Coghill and Raper developed methods for industrialized penicillin production and isolated higher-yielding strains of the Penicillium fungus. To improve upon that strain, researchers at the Carnegie Institution of Washington subjected NRRL 1951 to X-rays to produce a mutant strain designated X-1612 that produced 300 milligrams of penicillin per litre of mould culture, twice as much as NRRL 1951. In turn, researchers at the University of Wisconsin used ultraviolet radiation on X-1612 to produce a strain designated Q-176. This produced more than twice the penicillin of X-1612, but in the form of the less desirable penicillin K.
In 1973, Cold Storage's Pasaraya Malaysia, a joint venture of Cold Storage's subsidiary Supermarkets Malaysia and "Malaysian interests" was responsible for the construction of Jaya Supermarket in Petaling Jaya, set to be completed in April 1974. In 1985, Cold Storage Malaysia opened its first Majik Market store in Bangsar Baru, Kuala Lumpur, It operated under a franchise from Mumford Inc of Atlanta, USA, which complements its existing Jaya Supermarket chain but differ in concept and management. Due to competition from 7-Eleven, whose Malaysian franchise was then operated by the Antah Holdings group, Cold Storage Malaysia phased out Majik Market as part of its streamlining process. Cold Storage Malaysia, along with Peremba, Gaya Timur and Jusco were responsible for the initial version of Jaya Jusco "superstores" in 1985, with three stores in Dayabumi, Taman Tun Dr Ismail and Subang Jaya. In 1987, Cold Storage Malaysia, which had been through a difficult financial phase in the previous three years, had a change in management with some senior executives leaving. In 1992, DFI Retail Group purchased the company, although no major changes were made to the Cold Storage brand. Cold Storage started the Fresh Food Distribution Centre in Singapore in 1999, a composite multi-temperature warehousing for fresh and frozen food distribution. In 2023, DFI Retail Group divested its Malaysian food retailing business (including Cold Storage brand in that country) to Macrovalue Sdn Bhd.
2005: "Annual Sarkar Lecture" was established in Sarkar's honor to invite distinguished scientists to give lectures in the Research Institute of SickKids. 2006: Priyadaranjan Ray Memorial Award from the Indian Chemical Society. 2008: Visiting Professor, University of Hong Kong, Hong Kong. 2010: Fellow of IUPAC (International Union of Pure and Applied Chemistry). 2010: Fellow of the Royal Society of Chemistry, U.K. (FRSC (UK)). 2020: Sarkar Symposium, a celebration honoring Sarkar's 55 year career at SickKids. 2024: Order of Canada
Factors IIa, Xa, VIIa, IXa and XIa are all proteolytic enzymes that have a specific role in the coagulation cascade. Factor Xa (FXa) is the most promising one due to its position at the intersection of the intrinsic and extrinsic pathway as well as generating around 1000 thrombin molecules for each Xa molecule which results in a potent anticoagulant effect. FXa is generated from FX by cleavage of a 52 amino acid activation peptide, as the "a" in factor Xa means activated. FXa consists of 254 amino acid catalytic domain and is also linked to a 142 amino acid light chain. The chain contains both GLA domain and two epidermal growth factor domains (EGF like domains). The active site of FXa is structured to catalyze the cleavage of physiological substrates and cleaves PhePheAsnProArg-ThrPhe and TyrIleAspGlyArg-IleVal in prothrombin. FXa has four so-called pockets which are targets for substrates to bind to factor Xa. These pockets are lined up by different amino acids and Xa inhibitors target these pocket when binding to factor Xa. The two most relevant pockets regarding affinity and selectivity for the Xa inhibitors are S1 and S4. S1: The S1 pocket is a hydrophobic pocket and contains an aspartic acid residue (Asp-189) which can serve as a recognition site for a basic group. FXa has a residual space in the S1 pocket and is lined by residues Tyr-228, Asp-189 and Ser-195. S2: The S2 pocket is a small and shallow pocket. It merges with the S4 pocket and has room for small amino acids. Tyr-99 seems to block access to this pocket, so this pocket is not as important as S1 and S4.
Cellular and histone proteins bound to the DNA can be removed either by adding a protease or having precipitated the proteins with sodium or ammonium acetate or extracted them with a phenol-chloroform mixture before the DNA precipitation. After isolation, the DNA is dissolved in a slightly alkaline buffer, usually in a TE buffer, or in ultra-pure water.
Sources: en.wikipedia.org
A sealed container kept at room temperature and away from moisture is typical. Heat and humidity promote conversion to creatinine and can reduce assay values. Long-term storage under dry conditions helps maintain the original crystalline form.
Creatinine is a degradation product formed when creatine loses water and cyclizes. It can appear during storage, processing, or analysis if conditions are harsh. Quality specifications often set a maximum limit for creatinine to control purity.
No universal testing protocol applies across all markets. Some products follow pharmacopeial monographs, while others rely on manufacturer specifications and third-party certificates. Common tests include assay, water content, heavy metals, and microbial limits.
Solid product can remain within specification for years when stored dry and sealed, but expiration dates reflect manufacturer testing and regulatory conventions. Moisture and heat increase conversion to creatinine, so storage conditions matter more than the printed date alone. Degradation is gradual and can be monitored by purity testing.